Change of Translation Ratio in Consolidation (SEM BCS)

This year, while updating Currency Exchange rates, we have faced a problem with currency SLL (Leone of Sierra Leone) in case of increase of the FX rate more than 9.999 SLL to 1 EUR.

For example, till 01.01.2018 we used rate 9.600,00000 SLL to 1 EUR. Now we need rate 10.000,00000 SLL to 1 EUR.

But when we try to input rate we receive a message "Entry too long (enter in the format _ ___,_____)", because 1.234,56789 is a standard format for SLL rate.

To avoid this problem I see next approach: define since begin of 2018 time-dependent setting "Translation Ratio" (t-code OBBS) with factor 10 SLL:1 EUR instead of current ratio 1 SLL:1 EUR and use rate 1.000,00000 SLL instead of 10.000,00000 SLL to 1 EUR. But when I try to input new Translation Ratio I receive next message:

"Making changes to the table of translation factors may cause unwanted inconsistencies in your system. If you cannot avoid having to make changes while the system is in productive operation, it is essential that you read the following information.

A change of the currency conversion factors is to be avoided because it may produce unexpected results. When a change is unavoidable, it must be done with extreme care.

Rates are stored in the R/3 System with a direct or indirect link to a date (E.g. Value date, Document date, Entry date, etc.). Therefore, you may not change the factors of an existing entry in the factor table. You may only enter a new entry with new factors using a date so far into the future, that you can be sure that no rate for that date has been stored in the R/3 applications. For example, you make a new entry with new factors three months into the future.

For the effective date of your new factors you must enter a new rate in the exchange rate table."

I actually have old data (before 01.01.2018) used Translation Ratio 1 SLL:1 EUR. But, by the reason of time-dependency of setting "Translation Ratio", I do not expect any troubles with using of new ratio since 2018. From other point of view, I never used this approach earlier.

Maybe you can give any recommendation for this situation OR can recommend other approach? Thank you in advance.